Step 1

Roast the poblanos directly over a gas flame or under the broiler, turning, until charred all over. Transfer to a bowl, cover with plastic wrap and let cool. Peel, stem and seed the poblanos, then cut into 1/2-inch dice.

Step 2

Meanwhile, in a medium saucepan, combine the tomatillos, water, jalapeño, garlic and half of the onion and bring to a boil. Simmer over moderately high heat until softened, 5 to 7 minutes. Drain, reserving 1/2 cup of the cooking liquid.

Step 3

In a blender, combine the boiled vegetables with the cilantro and reserved cooking liquid and puree until smooth. Season with salt and pepper.

Step 4

In a large, deep skillet, heat the oil. Season the chicken with salt and pepper and cook over moderately high heat for 5 minutes, stirring occasionally. Add the remaining onion and the poblanos and cook, stirring occasionally, until the onion is just starting to brown, 5 to 7 minutes. Stir in the sauce and bring to a boil, then simmer over moderate heat until slightly thickened, about 5 minutes. Serve the chile verde with steamed rice, avocado and sour cream.